Our tunnel boring machine (TBM) Selina started her 5.5km journey from Chambers Wharf in early 2021. In April 2022, Selina reached her last stop at Abbey Mills Pumping Station, marking the end of tunnelling for the super sewer. With the tunnel finished, the team built a 24m-wide circular concrete ‘lid’ close to the shaft. In March 2024 the lid was lifted and moved into position on top of the shaft. At 12,000-tonnes, this manoeuvre is the heaviest lift on the super sewer project – surpassing the lifting of Tideway’s six tunnel boring machines earlier in the programme. Read more in our news article here.
The team is preparing to bring the tunnel into service by making a connection to the 6.9km Lee Tunnel, which has been in operation since 2016. The work involves breaking down and removing a 1.5m thick wall separating the Lee Tunnel from the Thames Tideway Tunnel, to create a single system which will protect the entire tidal Thames. To ensure the teams can work safely during these works, the Lee Tunnel must be taken out of service for a period of approximately two weeks.
Once the super sewer and the Lee Tunnel have been joined together, the team will work toward switching the system on, with combined sewage overflow points along the Thames being connected in a sequence – this is the commissioning phase, which is when the new infrastructure will begin to protect the river from pollution.
Commissioning will take several months. The system will be tested in different weather conditions at half capacity and then full capacity, ahead of full operation, which is due in 2025.